Molecular dynamics simulations of the temperature effect in the hardness on Cr and CrN films

Three-dimensional molecular dynamics (MD) simulations of nanoindentation technique was carried out for Cr and CrN thin films that present BCC and FCC crystalline structures respectively. Structures were oriented in the plane (1 0 0) and placed on silicon substrates. A pair wise potential was employed for simulating the interaction between atoms of each layer and a repulsive radial potential was used for representing a spherical tip indenting the sample. Mechanical properties of these two materials were obtained varying the temperature from 300 K to 1000 K with steps of 100 K. The hardness and elastic parameters were found for each temperature, showing a better mechanical response for films at low temperature. Structural changes evolution was observed presenting vacancies and slips as the temperature was increased. A temperature smoothing occurred because of the long range of slips and vacancies propagation. Then, the interatomic force decreases as the kinetic energy of the particles involved in nanoindentation process increases.